Does lion's mane really work for your brain?
Lion's mane shows cautiously positive signals for attention and working memory in small studies, but the evidence is still too thin to rely on. Until larger studies are available, you can safely try it as a capsule or powder, but do not expect a dramatic effect.
Two small studies in healthy young adults found improvements on cognitive tasks after a single dose of lion's mane. In a study of 41 participants, people responded faster on an attention task (Stroop) than after placebo. A second study found improved working memory, complex attention and reaction time 2 hours after taking 1 gram of extract. These are preliminary signals, not proof that the supplement works for everyone.
In older adults and people with mild memory problems, the picture is mixed. A systematic review of ten intervention studies found inconsistent results. There is only one small double-blind study in people with mild cognitive impairment that showed a temporary improvement, but it has not yet been confirmed by other research. There are also signals from three small human trials suggesting that cognitive decline in Alzheimer's disease may be slowed somewhat, but those studies are too small and too few to justify firm conclusions.
The active compounds in lion's mane, erinacines and hericenones, stimulate the production of nerve growth factor in cell and animal research, and have anti-inflammatory and neuroprotective properties. Whether those effects occur just as strongly in humans has not yet been sufficiently studied. Animal results do not automatically translate to humans.
On safety: powders or capsules appear to be safe and are relatively inexpensive. However, one case of a severe allergic reaction has been reported after eating fresh lion's mane. If you have a mushroom allergy, discuss this with your doctor. Moreover, cognitive supplements are not assessed in advance by regulators, and the marketing claims run far ahead of what science has demonstrated so far.
Based on two small RCTs in healthy young adults, one small RCT in people with mild cognitive impairment, a systematic review of 34 human studies (of which 10 were intervention studies), a narrative review of 3 human trials and 13 animal models, and mechanistic cell and animal research. No large independent RCTs are available.